Deliveries of Tesla's brand-new Model S electric sedan begin in the US this month, and buyers opting for the largest battery pack can add "cross-country adventure" to their roadtrip to-do list.

While the entry-level Model S lists an already impressive driving range of 250km from one charge of its battery pack, the American carmaker says you'll get around 480km if you go for the high-grade variant.

This week, the US Environmental Protection Agency (EPA) has released its own figures for the Model S, confirming a 265-mile range - 465 kilometres.

The department's mileage-measuring system is known as MPGe, which compares the distance a vehicle will drive on electric power to the equivalent energy in a gallon (3.78 litres) of petrol.

The US$77,400 top-shelf Model S variant, with its large 85kWh battery pack, gets an 89 MPGe rating. The US$57,400 entry-level model's 250km range is courtesy of a still large 40kWh battery pack.

By comparison, Nissan's all-electric Leaf carries a smaller 24kWh battery pack (contributing to the car's lower purchase price), and offers a driving range of up to 170 kilometres.

Ford's Focus Electric offers similar performance, with its 23kWh battery pack leading to a driving range of 150km from a single charge.

While the Focus Electric is not available in Australia (and is not expected in its current form), Nissan's Leaf is available now at $51,500.